Four bats dangling on a thin threads, creating nice shadows on the wall. The design was inspired by the images made for the unicorn plotter recently on thingiverse. For this bat mobile the same tricks are used to convert a picture into a single line as in the plotter images, but in this case the image is drawn using plastic (PLA/ABS). A total of 5 layers on top of each other gives some strength but leaves a very light object which creates nice shadows. See a very short movie here: http://www.youtube.com/watch?v=skxY-EhkV6c

IMPORTANT: Before you print the bats from the gcode file you must edit it. The gcode file is created using scripts to convert from an svg to an gcode file directly. The layer thickness is set to 0.3 mm, but parameters like the initial warm up procedure, possible homing, stopping of the heater at the end etc. are NOT included since this is different for each style of printer and for each material. I use a repstrap printer with makerbot electronics and firmware and PLA. Editing is not difficult. Compare a gcode file you have used successfully for some other print and use the header and tail(!) from that to complete the attached gcode file.

Print the bat four times.

The arms of the mobile are pure filament (PLA/ABS). I used PLA; in case the PLA is too curly from being on a spool, you can easily straighten it by putting it in some hot water in the sink and cooling it down on the sink while pulling it straight. When cooled down the filament will be straight.
The 2 arms are connected by a connector piece, the stl is attached below. Print using you own settings. Four connector pieces are printed in one file because the object is so small; choose the best one, it will need some cleaning up anyway. Check the full size of the lowest image on the left to see what it is supposed to look like.

The bats are attached to the arms using some thin thread secured by a tiny drop of glue. I used thin strands of PLA: let the extruder run and manually pull the hot filament out. The faster you pull, the thinner the thread!